L- and DL-Phenylglycines to treat diseases or conditions attributable to reduced carbohydrate metabolism

ABSTRACT

L- and DL-Phenylglycines of the formula ##STR1## and pharmaceutically acceptable salts thereof, wherein R is hydrogen or methyl and R 1  is NH 2 , OH or completes a carboxylic ester group, useful in treating certain cardiovascular diseases, diabetes and obesity.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 834,768 filedSept. 19, 1977, now U.S. Pat. No. 4,148,120.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to novel use of the compounds of formula (I) intreating mammalian subjects, including humans, suffering from diseasesor conditions which are characterized by reduced blood flow, oxygenavailability or carbohydrate metabolism in the cardiovascular system, orother diseases involving defects in carbohydrate metabolism,particularly obesity and diabetes. The compounds of formula (I) are wellknown in the art and methods for optical resolution of the racemicmixtures to obtain the L-isomers have been reported in, for example,U.S. Pat. Nos. 3,976,680 and 4,016,205 and references cited therein.

2. Description of the Prior Art

As mentioned above, the compounds of formula (I) are known compounds.Methods for the preparation of racemic 2-(4-hydroxyphenyl)glycine and2-(4-methoxyphenyl)glycine and their esters as well as the resolution ofthe esters into the D- and L-enantiomers are described in U.S. Pat. No.3,976,680. The same reference provides methods for hydrolysis of theresolved esters to provide the optically active acids of formula (I).

U.S. Pat. No. 4,016,205 discloses a process for resolving D- and andL-2-(4-hydroxyphenyl)glycine and reviews the prior art chemical andenzymatic methods for the resolution of the D-isomer.

The amides of formula (I) are readily obtained, for example, from thecorresponding acids via the acid chlorides by well-known methods, orfrom the corresponding lower alkyl esters such as the methyl ester, bytreatment with ammonia as described by Neilson and Ewing, Jour. Chem.Soc., Part C, 393 (1966) for preparation of optically activephenylglycines.

While the DL- and D- forms of the acids of formula (I) are known in theart to be useful intermediates in the preparation of penicillins andcephalosporins, no medical or any other use has been proposed for theL-isomers of formula (I), or any medical use for the racemic forms ofthese compounds.

SUMMARY OF THE INVENTION

The present invention provides a novel method of treating mammaliansubjects, including humans, suffering from a disease or conditionattributable to reduced blood flow, oxygen availability or carbohydratemetabolism, which comprises orally or parenterally administering to saidsubject a blood flow, oxygen availability or carbohydrate metabolismincreasing amount of the L- or DL-form of a compound of the formula##STR2## or a pharmaceutically acceptable salt thereof, wherein R ishydrogen or methyl and R¹ is NH₂, OH or completes a carboxylic estergroup. When R¹ completes said ester group, a particularly preferredvalue therefore is alkoxy having from one to five carbon atoms.Especially preferred such esters of formula (I) are methylL(+)-2-(4-hydroxyphenyl)glycinate and the corresponding isopropyl and3-methyl butyl esters of L(+)-2-(4-hydroxyphenyl)glycine.

An especially preferred phenylglycine of formula (I) isL(+)-2-(4-hydroxyphenyl)glycine. The D-isomers of formula (I), such asD(-)-2-(4-hydroxyphenyl)glycine are substantially ineffective and theL-isomers are consequently more effective than the DL- (racemic) formsat the same dose level.

Other particularly preferred compounds areL(+)-2-(4-methoxyphenyl)glycine and L(+)-2-(4-hydroxyphenyl)glycinamide.

The invention further provides a composition of matter in unit dosageform suitable for increasing blood flow, oxygen availability orcarbohydrate metabolism which comprises a pharmaceutically acceptablecarrier and from about 25 to 700 mg. of the L-form of a compound of theformula (I) or a pharmaceutically acceptable salt thereof.

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a novel method of treating an animal having adisease or condition attributable to reduced blood flow, oxygenavailability or carbohydrate metabolism in the cardiovascular system, orother disease or condition involving a defect in carbohydratemetabolism. While certain nonmammalian animals suffering from suchdiseases or conditions may benefit from treatment according to theinvention, the preferred subjects are mammals, including humans.Examples of diseases or conditions attributable to reduced blood flow,oxygen availability or carbohydrate metabolism in the cardiovascularsystem are ischaemic heart disease, particularly angina pectoris andmyocardial infarction; and cardiac failure. Regarding those diseases orconditions other than those primarily associated with the cardiovascularsystem and which involve a defect in the subject's carbohydratemetabolism, the compounds of formula (I) are especially effective in thetreatment of diabetes and obesity.

The invention also discloses a pharmaceutical composition comprising acompound of formula (I) or a pharmaceutically acceptable salt thereof,together with a pharmaceutically acceptable diluent or carrier, saidcomposition being in unit dosage form.

By the term "unit dosage form" as used herein is meant a physicallydiscrete unit containing an individual quantity of the active componentin association with a pharmaceutically acceptable diluent or carrier,the quantity of active component being such that at least one unit orseverable fraction of a unit is required for a single therapeuticaladministration. In the case of severable units, such as scored tablets,at least one severable fraction such as one half or one quarter of theunit may be all that is required for a single therapeuticadministration. It will be appreciated that the term "unit dosage form"does not include mere solutions except when the solutions are packagedin ingestible containers, e.g., soft capsules, or have been prepared soas to be suitable for parenteral administration, e.g., in vials ofsolution suitable for parenteral injection.

In said compounds of formula (I), when R¹ completes a carboxylic estergroup, it is preferably a group of the formula --OR² wherein R² is analkyl group having from one to five carbon atoms, a phenyl groupoptionally substituted by a member selected from the group consisting ofalkyl having from one to four carbon atoms, alkoxy having from one tofour carbon atoms, chloro, bromo and iodo; or an aryl substituted alkyl,said alkyl having from one to four carbon atoms and said aryl being aphenyl group optionally substituted by a member selected from the groupconsisting of alkyl having from one to four carbon atoms, alkoxy havingfrom one to four carbon atoms, chloro, bromo and iodo. In the compoundsof formula (I), when R¹ completes a carboxylic ester group, anespecially preferred value for --OR² is alkoxy having from one to fivecarbon atoms. Particularly preferred such esters are methylL(+)-2-(4-hydroxyphenyl)glycinate, isopropylL(+)-2-(4-hydroxyphenyl)glycinate and 3-methylbutylL(+)-2-(4-hydroxyphenyl)glycinate.

Pharmaceutically acceptable salts of compounds of the formula (I) may beaddition salts with acids containing pharmaceutically acceptable anions,e.g. the hydrochloride, hydrobromide, sulphate or bisulphate, phosphateor acid phosphate, acetate, maleate, fumarate, lactate, tartrate,citrate, gluconate, succinate, p-toluenesulphonate and carbonate salts.Pharmaceutically acceptable salts of compounds of the formula (I) inwhich R¹ is OH may also be salts containing pharmaceutically acceptablecations, e.g. the sodium, potassium, calcium, magnesium and ammoniumsalts, and salts with amines or amino acids, e.g., the salts witharginine, N-methylglucamine, ethanolamine, choline, triethanolamine,triethylamine, piperidine, pyrrolidine or diethylaminoethylamine.

As mentioned above, the phenylglycine derivatives of formula (I) areknown compounds. Methods for the preparation of the DL-compounds andtheir subsequent resolution into the D- and L-forms are well known (see,for example, U.S. Pat. No. 3,976,680).

The compounds of the formula (I) may be administered to patients inadmixture with or dissolved in a pharmaceutically acceptable carrierselected with regard to the intended route of administration andstandard pharmaceutical practice. For example, they may be administeredorally in the form of tablets or capsules containing a unit dose of thecompound of the formula (I) together with such excipients as cornstarch, calcium carbonate, dicalcium phosphate, alginic acid, lactose,magnesium stearate, talc, or certain complex silicates. The tablets aretypically prepared by granulating the ingredients together andcompressing the resulting mixture to tablets of the desired size. Thecapsules are typically prepared by granulating the ingredients togetherand filling them into hard gelatin capsules of the appropriate size tocontain the ingredients.

The compounds may also be administered parenterally, for example byintramuscular, intravenous or subcutaneous injection. For parenteraladministration, they are best used in the form of a sterile aqueoussolution which may contain other solutes, for example enough salts (e.g.sodium acetate, sodium lactate, sodium succinate or sodium chloride) ordextrose to make the solution isotonic. A pharmaceutically-acceptableorganic solvent such as polyethylene glycol or ethanol may also replacepart of the water. An antioxidant such as sodium metabisulphite may alsobe present, typically in an amount of up to 0.1% by weight. Suchparenteral formulations may be prepared by conventional methods. Forexample, in a typical procedure involving the preparation of asuccinate-containing intravenous formulation, a 0.2 molar solution ofsuccinic acid may be mixed with a 0.2 molar solution of sodium hydroxideto give a solution of pH 5. The compound of the formula (I) is thentypically dissolved in the succinate solution in an amount of 1-2% on aweight/volume basis. The resulting solution may then be sterilized, forexample, by filtration through a bacteria-proof filter under asepticconditions into sterile containers.

Alternatively, stable parenteral formulations based on isotonic salinesolution may be prepared by successively dissolving an antioxidant,e.g., sodium metabisulphite, and sodium chloride in nitrogen-spargedwater to give an approximately 0.1 molar sodium chloride solution,dissolving the compound of formula (I) in solution in an amount of 1-2%on a weight/volume basis and adjusting the pH to about 4 with 0.1 Nhydrochloric acid. The solution is then sterilized and filled intocontainers as already described. Suitable containers are, for example,sterile glass vials of an appropriate size to contain the desired volumeof solution, which volume will typically contain one or more unit dosesof the compound of the formula (I). The compounds of the formula (I) mayalso be administered by the infusion of a parenteral formulation asdescribed above into a vein.

For oral or parenteral administration to human patients, it is preferredthat the dosage level of the L- form of a compound of the formula (I)will be from about 0.5 to 10 mg./kg. and especially 2 to 5 mg./kg. for atypical adult patient (50-70 kg.), said dose being administered up to 5times a day. Thus, a typical unit dose would contain from about 25 to700 mg. of the active compound. Tablets or capsules will preferablycontain from about 25 mg. to 700 mg. of the active compound, one or moreof which would be taken orally up to 5 times a day. Dosage units forparenteral administration will preferably contain from 25-700 mg. of theactive compound in 5-20 ml. of solution and will thus contain from about5 to 35 mg./ml. of the L-form of said compound of formula (I). A typicalvial could thus be a 50 ml. vial containing from 5 to 35 mg. of theactive compound per ml. in 30-50 ml. of solution. The expected dosagelevel of the DL- (racemic) form of the compounds will, of course, behigher than that of the L-form.

It should, of course, be appreciated that the physician in any eventwill determine the actual dosage which will be most suitable for theindividual and it will vary with the age, weight and response of thepatient. The above dosages are exemplary of the average host. There may,of course, be individual cases where higher or lower dosage ranges aremerited.

The utility of the compounds of the formula (I) for treating disease orconditions characterized by reduced blood flow, oxygen availability orcarbohydrate metabolism in the cardiovascular system, or other diseaseor condition involving a defect in carbohydrate metabolism, particularlydiabetes and obesity, is assessed by their ability:

(1) to increase the oxidation of glucose and/or pyruvate by isolated ratmuscle preparations in vitro;

(2) to increase the proportion of the active form of the enzyme pyruvatedehydrogenase (PDH) in organs of animals in vivo;

(3) to reduce oxygen demand and affect the relative utilization ofcarbohydrate and lipid metabolites by the electrically-paced heart ofanesthetized dogs in the presence or absence of an isoprenalinestimulus; and

(4) to decrease blood glucose levels in animals made diabetic bychemical lesion of the pancreas.

Activity in tests for (1) illustrates the utility of the compounds inthe treatment of ischaemic heart disease, cardiac failure,maturity-onset diabetes or obesity. Activity in tests for (2) furtherillustrates their utility in the treatment of these diseases orconditions and, in particular, activity in an animal heart in vivodemonstrates utility in the treatment of ischaemic heart disease andcardiac failure. Activity in tests for (3) further illustrates theirutility in the treatment of ischaemic heart disease and cardiac failure.Activity in tests for (4) is a further measure of their utility in thetreatment of diabetes.

EXAMPLE 1

The compounds of formula (I) were tested for their ability to increasepyruvate oxidation as follows:

Diaphragm tissue is obtained from rats fed on a high fat diet similar to"Diet B" described by Zaragoza and Felber, Horm. Metab. Res., 2, 323(1970). Pyruvate oxidation by such tissue is assessed by measurement ofthe rate of incorporation of carbon-14 from carbon-14-labelled pyruvateinto carbon dioxide in vitro, as described by Bringolf, Eur. Jour.Biochem., 26, 360 (1972). The rate of pyruvate oxidation is depressed by50-75% compared with that by diaphragm tissue from rats fed on a normaldiet. When L(+)-2-(4-hydroxyphenyl)glycine is added to the medium, it isfound to stimulate pyruvate oxidation by diaphragm tissue from fat-fedrats in a dose dependent manner. The threshold concentration for suchstimulation is about 0.25 millimolar and a maximum stimulation of 170%is achieved at concentrations of 4 millimolar and above.D(-)-2-(4-hydroxyphenyl)glycine has no significant effect on pyruvateoxidation by diaphragm tissue from fat-fed rats at concentrations up to4 mM, while the DL (racemic)--compound has an effect approximately halfthat of the L(+)-isomer.

The degree of stimulation by other compounds of formula (I) at aconcentration of 0.5 mM is shown in the following Table:

    ______________________________________                                            Compound            % Stimulation                                         ______________________________________                                        L(+)-2-(4-methoxyphenyl)glycine                                                                       79%                                                   Methyl L(+)-2-(4-hydroxyphenyl)glycinate                                                              89%                                                   Isopropyl L(+)-2-(4-hydroxyphenyl)-                                            glycinate              34%                                                   3-Methylbutyl L(+)-2-(4-hydroxyphenyl)-                                        glycinate              32%                                                   L(+)-2-(4-hydroxyphenyl)glycinamide                                                                   51%                                                   ______________________________________                                    

The following compounds will also be found to stimulate pyruvateoxidation in the above test:

ethyl L(+)-2-(4-methoxyphenyl)glycinate

n-butyl L(+)-2-(4-methoxyphenyl)glycinate

L(+)-2-(4-methoxyphenyl)glycinamide

The D-antipodes of the above compounds will be found to have nosignificant effect on pyruvate oxidation.

EXAMPLE 2

The rate of glucose oxidation by isolated hearts from starved rats ismeasured in a recirculating oxygenated perfusion system, by measuringthe rate of incorporation of carbon-14 from carbon-14-labelled glucoseinto carbon dioxide using a method similar to those described by Morganet al., Jour. Biol. Chem., 236, 253 (1961) and by Randle et al.,Biochem. Jour., 93, 652 (1962). The perfusate contains glucose,palmitate, insulin and bovine serum albumen. The normal rate of glucoseoxidation is found to be 1.27±.32 micromoles/hour (mean of 9observations). When L(+)-2-(4-hydroxphenyl)glycine is included in theperfusate at a concentration of 2 millimolar, the rate of oxidation isincreased to 4.77±1.53 micromoles/hour (mean of 9 observations).D(-)-2-(4-hydroxyphenyl)glycine has no significant effect on the rate ofoxidation when included in the perfusate at the same concentration.

When the following compounds are employed in place ofL(+)-2-(4-hydroxyphenyl)glycine in the above test the rate of glucoseoxidation will be significantly increased.

L(+)-2-(4-methoxyphenyl)glycine

n-propyl L(+)-2-(4-hydroxyphenyl)glycinate hydrochloride

DL-2-(4-hydroxyphenyl)glycine, sodium salt

L(+)-2-(4-hydroxyphenyl)glycinamide

Glucose oxidation will not be significantly different from the normalrate when comparable levels of D-isomers of the above compounds areemployed.

EXAMPLE 3

The ability of the compounds of the invention to increase the proportionof the active form of pyruvate dehydrogenase enzyme has been measured inthe following test:

Rats fed on a high fat diet as in Example 1 are treated either withplacebo or with the compound of formula (I), by subcutaneous orintravenous injection or by oral administration, and at various timesafter treatment the rat hearts are removed and homogenized, underconditions which minimize changes in the proportion of the pyruvatedehydrogenase enzyme which is present in the active form, as describedby Whitehouse and Randle, Biochem. Jour., 134, 651 (1973). The totalamount of the enzyme present (PDHt) and the amount which is present inthe active form (PDHa) are assessed by a method similar to thatdescribed by Taylor et al., Jour. Biol. Chem., 248, 73 (1973). Thefat-feeding process is found to depress the ratio PDHa/PDHt from anormal value of about 0.7 to a value in the range from 0.05 to 0.2.Treatment of fat-fed rats with L(+)-2-(4-hydroxyphenyl)glycine, eitherparenterally or orally, increases this ratio in a dose-depenent manner,the threshold doses for this effect being 0.05 millimole/kg. byintravenous injection and in the range 0.1 to 0.2 millimole/kg. bysubcutaneous injection or by oral administration. The ratio is increasedto a value in the range 0.8-1.0 (i.e. above that for rats on normaldiet) by doses of 0.6 millimole/kg. and above.

D(-)-2-(4-hydroxyphenyl)glycine has very little effect at dose levels upto 1.2 millimole/kg., while the DL (racemic) compound, although havingsome activity, has only half, or less than half, the effect of theL(+)-isomer at the same dose levels.

The increase in the PDHa/PDHt radio effected by other compounds offormula (I) at a dose level of 0.6 millimoles/kg. is shown in thefollowing Table:

    ______________________________________                                                    Dosage PDHa/PDHt Ratio                                            Compound      Route.sup.1                                                                            Placebo    Compound                                    ______________________________________                                        Methyl L(+)-2-(4-                                                                           s.c.     0.13       0.69                                        hydroxyphenyl)                                                                              p.o.     0.13       0.42                                        glycinate                                                                     3-Methylbutyl s.c.     0.05       0.51                                        L(+)-2-(4-                                                                    hydroxyphenyl)-                                                               glycinate                                                                     L(+)-2-(4-hydroxy-                                                                          s.c.     0.16       0.93                                        phenyl)glycinamide                                                                          p.o.     0.16       0.91                                        ______________________________________                                         .sup.1 s.c. = subcutaneous                                                    p.o. = oral                                                              

In the above test the ratio PDHa/PDHt will also be significantlyincreased by the following compounds:

L(+)-2-(4-methoxyphenyl)glycinamide

methyl L(+)-2-(4-methoxyphenyl)glycinate gluconate

3-methylbutyl L(+)-2-(4-methoxyphenyl)glycinate hydrobromide

L(+)-2-(4-methoxyphenyl)glycine, potassium salt

EXAMPLE 4

The ability of compounds of formula (I) to reduce oxygen demand andaffect the relative utilization of carbohydrate and lipid metabolites inthe heart has been assessed by measuring the effect of the compounds onmyocardial blood flow and metabolism in fasted, closed-chest,anesthetized beagle dogs, with cardiac catherization to enablesimultaneous sampling of coronary sinus and arterial blood to be carriedout. Coronary sinus blood flow is measured by the hydrogen gas clearancetechnique described by Aukland et al., Circulation Res., 14, 164 (1964).The heart is paced electrically at 155 beats/min. and recordings ofhemodynamic parameters (blood pressure, left ventricular pressure andthe first derivative of the latter) are made continuously. Controlmeasurements of coronary blood flow are made and samples of blood takenat 40 minute intervals, both in an untreated animal and in the sameanimal dosed with an infusion of isoprenaline (60 mg./kg./min.), whichboth stimulates cardiac contraction and increases plasma free fatty acidlevels. The compound of formula (I) is then administered intravenouslyand measurements are made and samples taken again, 40 minutes and 90minutes later. The blood samples from the artery and coronary sinus areanalyzed for oxyhemoglobin, pyruvate and free fatty acid (FFA) content,differences between those of the arterial and coronary sinus blood, whenmultiplied by coronary blood flow, being a measure of oxygenconsumption, pyruvate uptake and FFA uptake by the myocardiumrespectively.

It is found that L(+)-2-(4-hydroxyphenyl)glycine at doses of 0.02 to 0.1millimole/kg. increases myocardial pyruvate uptake by at least 2-fold,both in the presence and absence of isoprenaline, for a period of atleast 90 minutes after dosing, in keeping with its proven action as aPDH stimulator. Myocardial flood flow is simultaneously increased by upto 150%, and myocardial oxygen consumption is decreased by about 20% inthe presence of isoprenaline. Myocardial FFA uptake is affected to avariable extent, but is generally decreased. There is no effect on anyof the hemodynamic parameters measured.

The following compounds will also be found to have effects similar toL(+)-2-(4-hydroxyphenyl)glycine on myocardial pyruvate uptake, bloodflow, oxygen consumption and FFA uptake in this test:

L(+)-2-(4-hydroxyphenyl)glycinamide

L(+)-2-(4-methoxyphenyl)glycine, calcium salt

methyl L(+)-2-(4-hydroxyphenyl)glycinate hydrochloride

3-methylbutyl L(+)-2-(4-hydroxyphenyl)glycinate.

The D-isomers of the above compounds will be found to have noappreciable effect on the above parameters.

EXAMPLE 5

The ability of compounds of formula (I) to decrease blood glucose levelshas been assessed by measuring their effect on blood glucose levels inrats in which diabetes has been induced by treatment with streptozotocin(85 mg/kg.). Four days after such treatment, a number of rats are given1 millimole/kg of the compound by intraperitoneal injection and asimilar number are given placebo. The doses are repeated after a further24 hours and 48 hours. Blood samples are taken from a tail veinimmediately before each dosage (which is 2 hours after removal of theanimals from food) and 1, 2 and 3 hours after the third dose. After 2days of treatment with L(+)-2-(4-hydroxyphenyl)glycine (i.e. immediatelybefore the third dose with 1 millimole/kg), blood glucose levels havebeen found to have declined from 378±8 mg/100 ml. to 356±4 mg/100 ml.,compared with a slight increase from 373±8 mg/100 ml. to 383±10 mg/100ml. for animals treated with placebo; while 2 hours after the third dosethe blood levels had declined still further, to a minimum value of 313±7mg/100 ml., compared with a value of 385±7 mg./100 ml. for animalstreated with placebo (all figures are averages for 8 animals).

L(+)-2-(4-methoxyphenyl)glycine as well as the corresponding amide,methyl, 3-methylbutyl and isopropyl esters will give similar reductionsin blood glucose levels. The corresponding racemic compounds of formula(I) will give a significant but smaller reduction in blood glucose.

When the D-isomers of 2-(4-hyroxyphenyl)glycine,2-(4-methoxyphenyl)glycine, and the corresponding amides, methyl,3-methylbutyl and isopropyl esters are employed, the values obtainedwill be comparable to those for the rats tested with placebo.

The preparation of unit dosage forms of the compounds of the inventionis illustrated by the following Examples.

EXAMPLE 6

Glacial acetic acid (12.0 gm.) and sodium acetate anhydrous (16.4 gm.)were each dissolved in 1000 ml. of freshly distilled water to produce0.2 molar solutions. 148.0 ml. of the acetic acid solution was thenmixed with 352.0 ml. of the sodium acetate solution and the mixture madeup to 1000 ml. with freshly distilled water.L(+)-2-(4-hydroxyphenyl)glycine (10.0 gm., 0.056 mole) was then addedand the resulting 1% w/v solution of L(+)-2-(4-hydroxyphenyl)glycine hada pH of 5. This was then sterilized by filtration through a suitablebacteria-proof filter under aseptic conditions into sterile 50 ml. glassvials, which when filled with 30 ml. of the final solution, contain 300mg. of the active ingredient.

EXAMPLE 7

Succinic acid (23.62 gm.) and sodium hydroxide (8 g.) were eachdissolved in 1000 ml. of freshly distilled water to produce 0.2 molarsolutions. 250 ml. of the succinic acid solution was then mixed with267.0 ml. of the sodium hydroxide and the mixture made up to 1000 ml.with freshly distilled water. L(+)-2-(4-hydroxyphenyl)glycine (10.0 gm.,0.056 mole) was then added and the resulting 1% w/v solution ofL(+)-2-(4-hydroxyphenyl)glycine had a pH of 5. This was then sterilizedas in Example 6. Sterile 50 ml. glass vials, when filled with 40 ml. ofthe final solution, contain 400 mg. of the active ingredient.

EXAMPLE 8

Citric acid monohydrate (21.0 gm.) was dissolved in 200.0 ml. of an 0.1molar solution of sodium hydroxide in freshly distilled water and theresulting solution was made up to 1000 ml. with freshly distilled andcooled water 963.0 ml. of this solution was then made up to 1000 ml.with an 0.1 molar solution of hydrochloric acid in water.L(+)-2-(4-hydroxyphenyl)glycine (10.0 gm., 0.056 mole) was then added togive a 1% w/v solution having a final pH of 5 at 23° C., which was thensterilized as in Example 6. Sterile 50 ml. glass vials, when filled with50 ml. of the final solution, contain 500 mg. of the active ingredient.

EXAMPLE 9

750 ml. of freshly distilled water were sparged with nitrogen and then6.0 g. sodium chloride, 300 mg. of sodium metabisulphite and 15 g. ofL(+)-2-(4-hydroxyphenyl)glycine were added successively and stirred todissolve. The pH was then adjusted to about 4.0 with 0.1 N hydrochloricacid, the solution made up to 1 liter with freshly distilled water andthe solution readjusted to pH 4.0±0.35 with 0.1 N HCl, to give a stable,1.5% w/v isotonic saline solution of the active compound. This wassterilized as in Example 6 and filled into sterile 50 ml. glass vials,which when filled with 50 ml. of solution each contained 750 mg. of theactive ingredient. A nitrogen blanket was maintained over the solutionthroughout and the vials were purged with nitrogen before and afterfilling.

EXAMPLE 10

Each of the above Examples 6 to 9 is repeated using twice the amount ofDL (racemic)-2-(4-hydroxyphenyl)glycine as that of the L(+)-isomer togive solutions containing twice the concentration of active ingredient.

EXAMPLE 11

The following are typical tablet or capsule formulations containingL-(+)-2-(4-hydroxyphenyl)glycine as active ingredient:

    ______________________________________                                                       mg./tablet or capsule                                                         A    B      C      D    E                                      ______________________________________                                        Active ingredient                                                                              500    100    100   25   25                                  Lactose          30     170    --   220  --                                   Corn starch      60      80    --   105  --                                   Microcrystalline cellulose                                                                     --     --     170  --   220                                  ("Avicel")                                                                    Glycine          --     --      80  --   105                                  Fine silica ("Aerosil")                                                                        --     0.35   0.35 0.35 0.35                                 Magnesium stearate*                                                                             5      3      3    3    3                                                  595  353.35                                                    ______________________________________                                         *9.1 blend with sodium lauryl                                                 "Avicel" and "aerosil" are Trademarks.                                   

For formulations A, B and D, the ingredients are thoroughly blendedtogether, and then either filled directly into hard gelatine capsules ofappropriate size, or granulated and compressed into tablets of thedesired size. For formulations C and E, the ingredients are thoroughlyblended together and slugged. The slugs are broken down into granules,and then either filled into capsules of the appropriate size, ordirectly compressed into tablets of the desired size.

In formulations A, B and D, the lactose may be replaced by equal amountsof calcium carbonate or dicalcium phosphate.

EXAMPLE 12

Example 11 is repeated using the same amount of DL(racemic)-2-(4-hydroxyphenyl)glycine as that of the L(+)-isomer. Ofcourse, twice as many capsules or tablets of this example may berequired to be taken for a single therapeutic administration as arerequired of the tablets or capsules of Example 11.

EXAMPLE 13

Examples 6 to 9 and 11 are repeated using equimolar amounts of thefollowing compounds in place of L(+)-2-(4-hydroxyphenyl)glycine:

L(+)-2-(4-methoxyphenyl)glycine

L(+)-2-(4-methoxyphenyl)glycinamide

Methyl L(+)-2-(4-hydroxyphenyl)glycinate

Isopropyl L(+)-2-(4-hydroxyphenyl)glycinate

2-Methylbutyl L(+)-2-(4-hydroxyphenyl)glycinate

L(+)-2-(4-hydroxyphenyl)glycinamide

EXAMPLE 14

Example 10 is repeated using equimolar amounts of the potassium andhydrochloride salts of L(+)-2-(4-hydroxyphenyl)glycine in place of thefree base.

EXAMPLE 15

Examples 10 and 12 are repeated but using equimolar amounts of thefollowing DL (racemic) compounds in place ofDL-2-(4-hydroxyphenyl)glycine:

2-(4-methoxyphenyl)glycine

2-(4-methoxyphenyl)glycinamide

methyl 2-(4-hydroxyphenyl)glycinate

isopropyl 2-(4-methoxyphenyl)glycinate

2-methylbutyl 2-(4-methoxyphenyl)glycinate

2-(4-hydroxyphenyl)glycinamide

It may advantageous to coat tablets according to the invention with anenteric coating, i.e. a coating of a material such as celluloseacetatephthalate or hydroxypropylmethyl cellulose phthalate which doesnot dissolve in the stomach but dissolves in the intestine, and toinclude in the tablet composition an effervescent material, e.g. sodiumbicarbonate and an edible acid such as tartaric acid, in order to avoidde-activation of the active ingredient in the stomach and/or intestineand to enhance the concentration of the active ingredient in the blood.

It may also be desirable to coat tablets with a sugar coating to improvepalatability.

EXAMPLE 16 Formation of Cationic Salts

L(+)-2-(4-Hydroxyphenyl)glycine, L(+)-2-(4-methoxyphenyl)glycine or thecorresponding DL-compounds are converted to the sodium, potassium,calcium, ammonium, magnesium, arginine, N-methylglucamine, choline,ethanolamine, triethanolamine, triethylamine, piperidine, pyrrolidine,and diethylaminoethylamine salts by reaction with an equivalent amountof the appropriate metal hydroxide, ammonium hydroxide or amine inwater, ethanol or mixtures of these solvents. The desired salt isisolated by filtration if it is insoluble or by evaporation of solventif the salt is soluble therein.

EXAMPLE 17 Formation of Acid Addition Salts

To a solution of L(+)-2-(4-hydroxyphenyl)glycinamide in ethanol is addedan equivalent amount of ethanolic hydrogen chloride. The resultingmixture is evaporated to dryness and purified by recrystallization fromethanol/ethyl ether.

By the above procedure any of the amino acids, amino esters or aminoamide of formula (I) are converted to the corresponding hydrochloridesalt or using the appropriate acid in place of hydrochloric acid thecorresponding hydrobromide, sulfate, bisulfate, phosphate, acidphosphate, acetate, maleate, fumarate, lactate, tartrate, citrate,gluconate, succinate, p-toluenesulfonate and carbonate salts are formed.

What is claimed is:
 1. A method of treating a mammalian subject suffering from a disease or condition attributable to reduced carbohydrate metabolism, which comprises orally or parenterally administering to said subject a carbohydrate metabolism increasing amount of the L- or DL- form of a compound of the formula: ##STR3## or a pharmaceutically acceptable salt thereof, wherein R is hydrogen or methyl and R¹ is OR², wherein R² is alkyl having from one to five carbon atoms.
 2. A method according to claim 1 wherein said compound is methyl L(+)-2-(4-hydroxyphenyl)glycinate, isopropyl L(+)-2-(4-hydroxyphenyl)glycinate or 3-methylbutyl L(+)-2-(4-hydroxyphenyl)glycinate.
 3. A method according to claim 1 wherein said subject is a human and from about 0.5 to 10 mg/kg of the L- form of said compound is administered up to five times a day.
 4. A method according to claim 3 wherein said compound is administered orally in the form of tablets or capsules each containing from about 25 to 700 mg. of said compound.
 5. A method according to claim 3 wherein said compound is administered parenterally in the form of a solution containing from about 5 to 35 mg. of said compound per ml. of solution. 